Purpose :
Thinning of the retinal nerve fiber layer (RNFL) is a marker of optic neuropathies including glaucoma. The aim of this study was to identify genetic variants that influence RNFL thickness in a healthy population.

Methods :
We used data from participants with complete genetic and phenotypic data from two population-based studies in Los Angeles, CA: the Los Angeles Latino Eye Study (LALES, n=2322) and Chinese-American Eye Study (CHES, n=1672). All participants were 49 years or older. RNFL thickness was measured during a clinic exam using the Optic Disc Cube 200x200 (RNFL) protocol in Cirrus HD-OCT (Carl Zeiss Meditec Inc.). LALES participants were genotyped on either the llumina OmniExpress BeadChip (730K markers) or Illumina Hispanic/SOL BeadChip (2.5M markers); CHES participants were genotyped on the Illumina HumanExome BeadChip (250K markers). The association between single nucleotide polymorphisms (SNPs) was assessed using an additive model adjusted for age, sex, and signal strength. Efficient Mixed-Model Association eXpedited (EMMAX) regression was used to account for population structure and hidden relatedness.

Results :
Results from LALES identified a suggestive association of the nasal quadrant RNFL with rs1900004 (p=1.06x10-7) on chromosome 10, which has been found to be associated with optic disc morphology, including vertical cup-to-disc ratio. Additionally, rs150161554 (p=5.93x10-7) within the gene ZNF331 on chromosome 19 and rs230935 (p=3.10x10-6), upstream of PMP22 on chromosome 18, were both associated with inferior quadrant RNFL. In CHES, we identified rs4268920 (p=2.49x10-6) within the GPC1 gene on chromosome 2 and rs12965928 (p=3.95x10-6) near 5’ of CNDP2 on chromosome 18 were associated with RNFL thickness in the superior quadrant.

Conclusions :
These results highlight the potential roles of genetic contributions to RNFL thinning. and indicate differences in these genetic effects by quadrant. Additionally, we identified a different set of genes responsible for RNFL thickness between Mexican Americans and Chinese Americans. These results warrant further studies to understand the complex linkage disequilibrium between ethnicities to identify the causal variants associated with RNFL thickness.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.